1. Field of the Invention
The invention relates, in general, to the field of magnetic sensors and accelerometers and the utilization of the same as magnetometers, magnetic compasses, range finders, navigational systems and other applications. More particularly, the invention relates to effective, simplified and highly accurate techniques for calibration of magnetic sensors and accelerometers.
2. Discussion of the Related Art
Currently available are a number of conventional magnetic sensor and accelerometer designs and techniques for utilizing them in compassing, navigational systems and other applications. In this regard, representative references include: Caruso et al., “A New Perspective on Magnetic Field Sensing” published by Honeywell, Inc. May, 1998 (hereinafter “New Perspectives”); a Honeywell Sensor Products Datasheet for the HMC1001/1002 and HMC1021/1022 1- and 2-Axis Magnetic Sensors published April, 2000 (hereinafter “Honeywell Datasheet”); a Honeywell Application Note AN-205 entitled “Magnetic Sensor Cross-Axis Effect” by Pant, Bharat B. (hereinafter “AN-205”); and a Philips Semiconductors publication entitled: “Magnetoresistive Sensors for Magnetic Field Measurement”, published Sep. 6, 2000 (hereinafter “Philips Publication”). The disclosures of these references are herein specifically incorporated by this reference in their entirety.
Specifically, the New Perspectives document provides an overview of magnetoresistive and other magnetic sensing technologies while the Honeywell Datasheet provides a detailed description of the particular magnetoresistive sensors as may be utilized in a representative embodiment of the present invention disclosed herein. The AN-205 application note describes conventional techniques for the elimination of magnetic cross-terms in magnetoresistive sensors while the Philips Publication provides a detailed description of magnetoresistive sensor functionality including relevant mathematics.
Accelerometers are known in the art. Some conventional accelerometers include VTI Technologies, SCA 3000 series accelerometer, ST Microelectronics, LIS 302 series accelerometer and Analog Devices, ADXL 103 and ADXL 203 series accelerometers.
There is currently a need for calibration techniques that are effective, simplified and highly accurate in order to calibrate magnetic sensors and accelerometers utilized in magnetometers, magnetic compasses, range finders, navigational systems and other applications.